Space telegraphy.



' S. CABOT.

SPACE TELEGBAPHY.

AIPLIOATION nun JULY 20, 1906. nnmzwzn In. 2. 1912.

1,021,132. Patented Mar. 26, 1912.

PATENT OFFICE.

SEWALL CABOT', F BROOKLIIIE, MASSACHUSETTS.

SPACE 'I'ELEGRAPHY.

Specification of Letters Patent.

Patented Mar. 26, 1912.

Original application filed Noyember 18, 1905, Serial No. 288,032. Divided and this application filed July 20, 1906, Serial No. 326,985. Renewed January 2, 1912. Serial No. 669,180.

To'all whom it may concern Be it known that I, SEWALL (hear, a citizen of the United States, and a resident of Brookline, in the county of Norfolk and" State of Massachusetts, have invented a new other by means of electromagnetic waves without the use of wiresto guide the waves to their destination; and it relates more particularly to a method of transmitting and receiving such waves.

The object of the present invention is to realize a method of eflecting the well known operation of breaking, such as used today in Wire telegraph traflic and as worked out in duplex and quadruplex systems, 1n

the handling of wireless telegraph traffic.

With this object in view my invention comprises a method of signaling-by electromagnetic waves which consists, first, in rendering a receiver inoperative, in automatically short-circuiting the receiving system which is, connected with the transmitting system at a point having zero potentialto ground during transmission and in connecting the transmitting system directly to earth, thereby automatically putting said transmittingsystem in condition for trans mitting by a movement of a key in one direction, and then developing electrical oscillations in said transmitting system by a further movement of said key in said direction; and, second, stopping the development of electrical oscillations by a movement of said key in the opposite direction, in automatically' opening the short-circuit around the receiving system and breaking the direct connection of the transmitting system to earth,and then putting said receiver in operative condition by a further movement of said key in said-opposite direction; and,

- finally, ascertaining between signal elements,

when said key is in normal position and said receiver is 1n operatlve cond1t1on,1f break signals are being transmitted from a distant transmitting system. s For the purpose of more fully disclosing my invention, I have illustratedand shall particularly describe one specific organization of apparatus and circuits whereby the same may be carried into effect; but it is to be understood that my invention is broader than mere a paratus and that it may be carried into e ect by a great variety of apparatus and circuit arrangements, some of which have been illustrated and particularly described in my application Serial No. 288,032, filed Nov. 18, 1905, of which this application is a division and upon which lihitg'nt No. 840,908 was granted January 8,

The figure is a diagram representing an organization of apparatus and circuits whereby the hereinbefore stated method may be reahzed in practice.

- In the figure V is a vertical, or elevated conductor, which may consist of one or of any number of conductors.

E E are earth connections.

C C, C C are condensers.

L ,is an inductance coil.

M is a transformer whose primary and secondary windings I and I are preferably so spatially related as to produce a transformer of large magnetic leakage. spatial relation is herein shown for the sake of clearness as a transverse separation, although in practice the separation is axial M is a'transformer adapted to raise the potential impressed upon its primary winding I to a very high potential in its secondary winding I',.

M is a transformer whose primary and secondary windings I, and I are preferably so spatially related .as to produce a transformer of large magnetic leakage. Here, again, the separation of the coils is for the sake of clearness shown as a transverse separation, although in practice the separation preferably is axial.

P is an oscillation responder of any suit able kind, and herein illustrated as an electrolytic cell, the anode W of which is the well known Wollaston electrode.

T is a telephone or other suitable signalindicat-ing device.

It is a resistance forming with the battery B and adjustable contact 70" 'a potentiometer.

- A is an alternator or other suitable source of. vibratory current. v

In wireless or space telegraphy, as in telegraphy b connecting wires, it is often desirable liar the receiving operator to interrupt. the transmitting operator, that is to say, if the receiving operator should fail to The I that a portion of the understood. In wire telegraphy, especially.

understand a portion of a message it is desirable that he should be able immediately to notify the transmitting operator of the factso that the latter may repeat that portion of the message .which the former failed to understand, instead of having to wait until the transmitting operator has finished sending the message and then notifying him message had not been as developed in the practical operation of the duplex and quadruplex systems, this is accomplished very simply in a manner well known to those skilled in the art of telegraphy; but in wireless telegraphy the peculiar difiiculties involved in arranging the circuit connections in transmitting and receiving systems, as-well as the differences between said circuit connections, and also the extreme sensitiveness of the oscillation responder, render the operation of breaking more difiicult and, so far as I am ad'- vised, no operative system has yet been de- -vised whereby the operation of breaking may be effected.

In the particular apparatus herein illustrated I carry out my method by means of a sending key or other sending device provided with auxiliary mechanism, whereby such key or device performs aseries of functions in a definite order.- These are,

first, rendering the responder or receiver ing inoperative at the beginning of the down stroke of the key, automatically short-cir cuiting the receiving system and connectthe transmitting system directly to earth and then closing the power circuit.

In that particular organization of apparatus and circuits which I have chosen for more fully disclosing the method which constitutes the subject matter of the present forming its natural functions, and in View" of the fact that many ways of rendering the receiver inoperative will readily occur to those skilled in the art, it is not my intention to limit myself to the particular means disclosed since I, consider any suitable means within the scope of my invention. Itwill also be understood that any suitable form of oscillation detector may be substituted for that particular form herein shown in carrying out my method of breaking.

Referring to vthefigure, upon the depression of the key K for the purpose of sending a signal, the first operations efiected are the separation of the two contacts which in the normal position of the key are closed at 7:", and the opening of the circuit is I, P W T k thereby rendering the receiver P inoperative or incapable of responding, and the closure of. the contact is herein shown as a screw cooperating with a spring. These two operations may be simultaneous or successive, all that is necessary being that they occur prior to the closure of the contact is and the consequent energization of the transmitting circuit. The closure of the circuit 7" B at the point 70 energizes the relay 9 and causes the armature it, normally held against its backstop ?2, to close the contact 76', thereby connecting the transmitting system directly to' earth and automatically short-circuiting the receiving system between the points 0 0-. The, transmitting system now being connected directly to earth, the receiving system being short-circuited, and the circuit i of the receiver being opened, the system is in condition for transmitting and the further depression of the key K eifectssuch transmission by the closure of the circuit containing the source of energy A, the primary of the high potential transformer M and the contact is, thereby energizing the transmitting system, andiproducing the disruptive discharge of the condenser G across the multiple series spark gas S.

At the point 0 the receiving system is connected to the transmitting system and it will be noted that during the operation of the transmitting system this point has zero potential to ground because during transmission this point is connected to earth by a conductor o 0 E of zero impedance, so that the potential of the receiving system as a whole is practically zero. It will also'be noted that during transmission, even when oscillations of large current value are be ing developed in the elevated transmitting conductor system E 0 60 I V, there is developed between the points 0 0-,.which form the terminals. of the receiving system, practically no difference of potential, or at least not a suificient difference of potential to damage the delicate parts of the receiving apparatus. So far as I am aware, no combined transmitting and receiving system heretofore has been devised inwhich the receiving system is connected to the transmitting system at a point which duringtransmission has zero potential to. ground. This feature of the apparatus whereby the present method may be realized is very important, inasmuch as thereby the operators may retain their head telephones T in position during transmission with safety.

When the operator has depressed the key to its fullextent for a sufiicient length of time to produce the desired signal element,

the key is allowed to regain its normal ponection of the transmitting system to earth.

The object of making the relay 1- sluggish in its action as well as providing for the time interval between the opening of the contacts is and 7.: is to permit the complete subsidence of electrical movement in the transmitting system before breaking its connection to earth. Simultaneously with the denergization of the relay r, or before or after such dene'rgization, the contact is is closed and the receiver thereby is rendered operative.

An appreciable interval of time must elapse between the sending of signal elements, and. it is during such interval of time when thekey is in its normal position that the sending operator, who sends with the head telephone T placed over his ears, may ascertain that the receiving operator at the distant station is signaling break. Said,

receiving operator having failed to understand a portion of the message transmitted to his station, depresses his sending key immediately upon such failure to understand a word or a portion of the message and sends a predetermined signal indicating that he wishes the transmission stopped. The waves sent out by said receiving operator develop in the vertical at the station from which the message is being sent to said receiving oper ator electrical oscillations which pass to earth E by way of the secondary I. which for said oscillations operates merely as an inductance, the coil L and the parallel branch circuit I 0,, when the key K is in its normal position and the contact 70 accordingly is open. Said oscillations are of such Copies of this patent may be obtained for frequency that for them the elevated receiving conductor system VI. L I," C, E has zero reactance, so that currents of relatively large amplitude are developed in the resonant receiving circuit and create at the terminals of the condenser C a'sufiicient difference of potential to cause the oscillation responder 1 to respond and produce a signal in the telephone T. This signal is an indication to the transmitting operator that the receiving operator is signaling break, and he thereupon ceases his transmission and receives from the receiving operator instructions concerning the repetition desired by said receiving operator. If the oscillations created in the elevated conductor by the wave sent out from the distant receiving station at which the operator who desires to break is located, are so created when the key is down, it is-obvious that such oscillations will not produce any response in the receiver P; but it will be observed that as soon as the key is again in its normal position the oscillations will affect the receiver and the'trans'mitting operator will then re ceive the break 'signals and cease to send. As indicated, one terminal of the spark gap S may be connected to earth at E so as to give he same practically zero potential to earth.

I claim The method of signaling by electromagnetic waves which consists in short-circuiting a receiving system between two points of a transmitting system across which exists a practically zero diti'crence of potential during transmission and which have a practically zero potential to earth during transmission, developing electrical oscillations in said transmitting system, and then stopping the development of said electrical oscillations and opening said short circuit during the transmission of eachsignal element.

In testimony whereof, I have hereunto subscribed my name this 18th day of July 1906.

SEl/VALL CABOT.'."

W itnesses:

(Hanna-1s E. HAYwoon, Geo. K. Woonwon'rn.

five cents each, by addressing the "Commissioner of Patents, Washington, D. C." 

